Abstract : The chemical and the particulate stability of refractory oxides, nitrides, and carbides in tungsten were investigated by thermogravimetric, X-ray diffraction analyses and replication. Alloys were prepared by powder milling and hot pressing, which was established as a simple and effective method of consolidation. The tensile properties of successfully extruded and swaged alloys were determined on a screening basis in the temperature range 1650 to 2400 C. The refractory dispersoids were found to be chemically inert in pure tungsten to 2200 C, but none of them exhibited complete particulate stability under all processing and annealing conditions; e.g., particle growth occurred in all systems during hot pressing. Contaminants like tungsten oxides, oxygen or carbon were found to be very effective at relatively low temperatures in changing the chemical composition of the dispersoids. The limited number of high temperature tensile and creep tests conducted has established W-ThO2 alloys as being superior to any of the other alloys. The latter result is attributed to the retention of a fine particle population in the size range 200-1000A. (Author)